Emitter plane and backlit pusbuttons

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treddie
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By the way, here is an image of the type of pushbuttons I was trying to simulate:
PBs.jpg
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FooZe
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Oh, i see, yes these are different to what i had in mind.

Here is what i came up with when going down the mix material road, glossy combined with the specular.
Note that i also changed the emitter to be a bulb shaped sphere and changed the plane of the old emitter to be a highly reflective surface.
redBacklitButton.jpg
Hopefully it's more along the lines of what you are after?

I think in this case it's just that scattering is not as effective as just a high roughness. I didn't write the code so I can't comment on mathematically exactly what it is doing but it would seem this initial interaction on the surface spreads things a lot more than scattering does, without diminishing light intensity.

I think this ties into your problems with the color of your lights too - because you may be needing to increase the light intensity to compensate for the scattering. As you increase the intensity of an emitter, you will probably have noticed that there is a clipping point at which the light seemingly becomes over-exposed and starts to increase in temperature. So even a red light source, with excessive power, will start turning white (and travel through orange on the way).

This is definitely not an easy material to simulate!

Cheers
Chris.
Attachments
PushButton-Red.zip
(580.07 KiB) Downloaded 148 times
treddie
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Hey, thanks for the post and the great image. That's EXACTLY what I was trying to achieve. I also like your idea of having that highly reflective back surface to help "push" the light forward.

However, on the red problem, I can understand how the color temperature increases with power and tends toward the oranges and yellows, but if the material of the plastic is red, then it seems that the yellow wavelengths should not be able to pass through the plastic. In other words, the light getting through should only be the red wavelengths. We've all seen a red pushbutton, and the lamp is putting out a lot of power without there being any yellowing at all in the illumination, like these:
Red Pushbuttons.jpg
There HAS to be something wrong with the way red is handled. I can lower the power back to almost zero and I still get orange to yellow. If I cut the distribution back to near zero as well, it does not seem to go as far into the yellow as before, but still very orange. That just isn't behaving naturally.
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treddie
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Found a better answer to the red problem in the manual. I was using RGB Spectrum for my colorizing. But Gaussian Spectrum works better since you can set your center wavelength that you want the color to be, then set width to a real low value so that the wavelength band is very narrow. It still does not work at higher power levels, so the red pushbuttons look noticeably dimmer than the others if you want to stay really red. If you try to kick the power up, you still get yellowing, even though you have specifically chosen a width of close to zero.
Win7 | Geforce TitanX w/ 12Gb | Geforce GTX-560 w/ 2Gb | 6-Core 3.5GHz | 32Gb | Cinema4D w RipTide Importer and OctaneExporter Plugs.
treddie
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Fooze, I am curious what GPU you are using and the rough render time it took to render your sample. Very smooth looking.

Also, in coming back here, just now saw your attachment! Maybe you can suggest a good opthamologist. :))
Thanks for the upload.
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FooZe
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Hi, Sorry for the late reply.

Sorry, i can't remember the render time - i just left it while i was checking emails/working on website stuff and being generally busy :)
I think at the time i was using a single 580, however i have 2 in my machine at the moment.

So this was about 3min on 2x580's
timeTrial.png
...Hotpixel removal at about 0.45, alpha shadows off.

Note this one is a png, I think conversion to jpg (as i did for the last one) tends to smooth the image too.

Cheers
Chris.
treddie
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Dang, that seems awful fast. My testing with someone else's machine seemed to indicate that a single 580 was only about 1.5x the speed of my 560.
I'm confused.
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FooZe
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Alpha shadows off i am getting about 9.16Ms/sec with all other settings as per the ocs.
Octane 2.58e - 2x580's

4.59Ms/sec with just one 580.

Cheers
Chris.
treddie
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This might be comparing apples to oranges, but in a render I am doing right now, there are 18 of those pushbuttons that are lit, with 23 that are not lit, plus other stuff going on. Assuming I was using a single 580, would I still see the same Ms/sec as compared to the single pushbutton test, or close to it? In other words, would any card still be pushing the same amount of samples per second, regardless of how complex the scene is?
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FooZe
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Nope you won't get the same speed, scene complexity does matter.

Cheers
Chris.
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